What do we learn from lithium-rich giants in GALAH? Read the paper: Sarah Martell, Jeffrey Simpson, Adithya Balasubramaniam, and the GALAH team MNRAS 505:5340 Get the GALAH data: galah-survey.org Twitter updates: The challenge: There are multiple processes that have been The conclusions: Trends between lithium enrichment, @galahsurvey proposed as the source of lithium enhancements in evolved metallicity, and rapid rotation indicate that stellar structure stars. Because lithium-rich giants are so rare, large samples modulates lithium production. The helium flash may from surveys like GALAH and LAMOST are crucial to produce lithium in all stars. Further monitoring is needed to understand which processes are at work in which stars. test hypotheses about binary stars. There are four kinds of lithium-rich giants What do we already know? Luminous red giants: Steadily expanding atmosphere and Red clump stars degenerate helium core. Lithium is a fragile element: These stars may gain lithium by produced during Big Bang engulfing gas giant planets or Nucleosynthesis, it is almost because of rapid rotation. exclusively destroyed by stars Red giant branch stars at the Only 1% of red giant stars luminosity bump: (red box) in the GALAH DR3 Internal structure is adjusting after catalogue (background Red giant branch stars an injection of fresh hydrogen into distribution) are lithium-rich the H-burning shell. (red dots) or super lithium- These stars may transport lithium rich (black dots). out from the interior as they re- equilibrate. What is new in the GALAH data?

The probability that a star will be lithium- Rapid rotation is associated with higher rich is higher at higher metallicity lithium enrichment in red clump stars Red clump Red giant stars branch stars Red clump stars Secondary red clump stars: Red clump stars: More massive than the regular red Finished with the red giant branch, clump, began core helium burning have recently undergone the helium without a flash. flash to ignite core helium burning. These stars may be producing These stars may be evidence for a lithium because of torques from new process that enriches all RC binary companions. stars in lithium. Binary companions A red clump star is more than twice as and rotation-driven mixing may also likely as a red giant branch star to be be important. lithium-rich